Testing JDK 9 EA with Heroku

You can test JDK 9 in just a couple of minutes by deploying any JVM-based app to Heroku.

Why should you test JDK 9? Because it’s a great way to help the community! The Adopt OpenJDK project is eagerly requesting feedback, bug reports, and contributions that help get everyone’s frameworks and applications prepared for the new release.

You can test your own app, or use one of Heroku’s samples. If you’re not familiar with Heroku, you might want to follow the Getting Started with Java on Heroku guide.

When you have an app ready, add a system.properties file in the root directory of your project, and put this code in it:


Add that file to your Git repository by running these commands:

$ git add system.properties
$ git commit -m "Testing JDK 9"

Then, deploy to Heroku by running git push heroku master:

$ git push heroku master
Counting objects: 3, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 313 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote: -----> Java app detected
remote: -----> Installing OpenJDK 1.9... done

You’ll see Heroku install JDK 9 for your app, and once the deploy is finished you can check things out by running:

$ heroku open
$ heroku logs -t

And you can start a shell for your app and test the new JDK 9 by running:

$ heroku run bash
Running `bash` attached to terminal... up, run.1713
~ $ java -version
openjdk version "1.9.0_ea-cedar14_2015-07-16"
OpenJDK Runtime Environment (build 1.9.0_ea-cedar14_2015-07-16-b72)
OpenJDK 64-Bit Server VM (build 1.9.0_ea-cedar14_2015-07-16-b72, mixed mode)

If you find any problems, feel free to reach out to me.

If you don’t find any problems, and still want to contribute, try collecting some data points for the G1GC (the new default garbage collector) as describe in this post on hotspot-dev.

If you’d like to play around with some new features, check out this great post on what’s new in JDK 9 from Takipi.